1. Field of the Invention
The present invention relates to an image inputting device for picking up an image of an object to be photographed, which is placed on a stage or base.
2. Description of the Related Art
The so-called document camera is known as an image inputting device for picking up an image of an object to be photographed, e.g., a document, placed on a stage.
A conventional document camera (image inputting device) will be described below with reference to FIGS. 17 and 18. FIG. 17 shows the document camera in a state of photographing a document, and FIG. 18 shows the document camera during a collapsing, or folding, step.
In those drawings, a document stage 102 is formed on a document stage unit 101, and a document 102a is placed on the document stage 102. A control panel 103 manipulated for instructing the operation of the document camera is made up of electrical switches, etc.
A rotary shaft 105a is provided at a base end of a lower camera arm 105. The lower camera arm 105 is held on the document stage unit 101 such that it is rotatable about the rotary shaft 105a in a direction of an arrow L in FIG. 17.
An upper camera arm 106 is axially telescopically coupled to the lower camera arm 105.
An image pickup unit 107 is mounted to a fore end of the upper camera arm 106. A photographing lens 108 is disposed in the image pickup unit 107 for taking an image of the document 102a. The image pickup unit 107 is supported by a shaft provided at a fore end of the upper camera arm 106 such that it is rotatable about the shaft in a direction of an arrow J in FIG. 17.
A right illumination unit 109 is mounted to a right illumination arm 110, and a fluorescent lamp 109a is attached to the right illumination unit 109. The right illumination arm 110 is held on the document stage unit 101 such that it is rotatable in a direction of an arrow N in FIG. 17.
Also, the right illumination unit 109 is supported by the right illumination arm 110 such that it is rotatable in a direction of an arrow Q in FIG. 17.
A left illumination unit 111 is mounted to a left illumination arm 112, and a fluorescent lamp 111a is attached to the left illumination unit 111. The left illumination arm 112 is held on the document stage unit 101 such that it is rotatable in a direction of an arrow M in FIG. 17. Also, the left illumination unit 111 is supported by the left illumination unit 112 such that it is rotatable in a direction of an arrow R in FIG. 17.
An unlocking lever 113 unlocks a locking mechanism (not shown) for locking the lower camera arm 105 to the document stage unit 101. By moving the unlocking lever 113 in a direction of an arrow O in FIG. 17, the locking mechanism is unlocked from the lower camera arm 105.
How to take an image of the document 102a with the document camera is now described. In the photographing state, as shown in FIG. 17, the photographing lens 108 is positioned right above the document stage 102 to face exactly downward. As a result, the image pickup unit 107 holding the photographing lens 108 is also properly positioned.
A photoelectric transducer (not shown), such as a CCD, is disposed in the image pickup unit 107 at a focused position of the photographing lens 108, and an electrical signal output from the photoelectric transducer is converted to an image signal by a control circuit (not shown). Then, the image signal is output to an image display unit (not shown), such as a projector, which is electrically connected to the document camera.
Further, in the state shown in FIG. 17, an illumination level of the document 102a can be adjusted by rotating the right illumination unit 109 and the left illumination unit 111 respectively in the directions of the arrows Q, R in FIG. 17.
A manner of collapsing the document camera will now be described. When collapsing the document camera from the state (photographing state) shown in FIG. 17, the image pickup unit 107 is first rotated in the direction of the arrow J in FIG. 17. Then, by pushing the upper camera arm 106 into the lower camera arm 105 (in a direction of an arrow K), the overall length of the camera arm is shortened so that the image pickup unit 107 moves closer to the document stage 102. Subsequently, the unlocking lever 113 is moved in the direction of the arrow O to unlock the lower camera arm 105 from the document stage unit 101. The lower camera arm 105 is rotated about the rotary shaft 105a in the direction of the arrow L, causing the image pickup unit 107 to lie over the document stage 102.
At a position just before the image pickup unit 107 comes into contact with the document stage unit 101, the positional relationship between the image pickup unit 107 and the document stage unit 101 is automatically fixed again. Further, by moving the unlocking lever 113 in the direction of the arrow O in the fixed state, that fixed state is released, whereupon the lower camera arm 105, i.e., the image pickup unit 107, is allowed to move relative to the document stage unit 101.
Next, the left illumination arm 112 is rotated in the direction of the arrow M, and the left illumination unit 111 is rotated in the direction of the arrow R, as shown FIG. 18. A resulting folded-up state is shown FIG. 18.
Then, the right illumination arm 110 and the right illumination unit 109 are rotated in the direction of the arrow N from the above-mentioned state. Thereafter, the right illumination unit 109 is rotated in the direction of the arrow Q so that the volume of the document camera in its collapsed state is further reduced. In this way, the left and right illumination units are folded and the document camera is brought into a collapsed state (not shown).
The operation of unfolding the document camera from the collapsed state to the photographing state is carried out by reversing the above-described operation of folding the document camera from the photographing state to the collapsed state.
However, the conventional document camera has a relatively low mechanical strength in its collapsed state. More specifically, because the image pickup unit 107, the left and right illumination units 109, 111 (in particular fluorescent lamps 109a, 111a), and the control panel 103 are exposed to the exterior, there is a risk that the image pickup unit 107, the left and right illumination units 109, 111, and the control panel 103 may be damaged in the collapsed state of the document camera upon accidental impacts applied to any of those components. Another problem is that the photographing lens 108 is more easily susceptible to flaws and contaminations.
Those problems can be avoided or relieved by placing a protective cover so as to cover the overall upper surface of the document camera, and/or by fitting a lens cap to the photographing lens 108. However, the necessity of such a dedicated protective member is disadvantageous in that the structure of the document camera is more complicated and the number of extra parts is increased.
Also, in the conventional document camera, since the upper camera arm 106 is telescopically pushed into the lower camera arm 105 for contraction, an electrical signal line (not shown) passing through both the camera arms 105, 106 for electrical connection between the image pickup unit 107 and the document stage unit 101 must be wired with such a sufficient allowance as causing the line to loosely slack in the collapsed state. In that situation, there is a risk that the electrical signal line is more likely to break with repeated operations of extending and contracting the upper camera arm 106 and the lower camera arm 105.
If the upper camera arm 106 and the lower camera arm 105 are constructed as a one-piece camera arm to prevent the above-mentioned problem, the image pickup unit 107 would project out of the document stage unit 101 (for example, forward of the control panel 103) when the document camera is in the collapsed state. This would result in the problems that the document camera in the collapsed state has a larger size and the document camera is more easily susceptible to a failure because external impacts are more likely to impose on the image pickup unit 107, which has a relatively low mechanical strength, when the document camera is in the collapsed state.
In the above case, to prevent the image pickup unit 107 from projecting out of the front portion (control panel 103) of the document stage unit 101, the size of the document stage unit 101 must be further increased.
Moreover, since the document resting surface of the document stage 102 is exposed to the exterior in the collapsed state of the document camera, the document resting surface is susceptible to contaminations.